1. Field of the Invention
This invention relates to rolling machines and more particularly to controlled deflection rolls comprising an inner nonrotative shaft having a roll shell journaled about it, the inner shaft having hydrostatic bearings directed against the inner surface of the roll shell.
2. Description of the Prior Art
This invention is generally related to a co-pending U.S. application Ser. No. 583,860, filed June 4, 1975 now abandoned, and assigned to the assignee of the present invention. That invention includes an arrangement to externally bend the inner nonrotating shaft of the deflection roll, wherein deflection sensors control the amount of bending, the inner shaft bending in a manner to counter any deflection incurred in the roll shell.
An earlier invention assigned to the present assignee is U.S. Pat. No. 3,587,152, which involves a controlled deflection roll having one or more radially acting pressure applying pistons. Each piston has a hydrostatic bearing pad on its radially outer end. The bearing pad has a curvilinear surface that supports the inner surface of the roll shell with pressurized fluid providing a lubricant therebetween.
A fluid bearing table roll is described in U.S. Pat. No. 3,869,774 wherein an elastomeric ring is disposed radially outwardly of an annular bearing ring member. U.S. Pat. No. 3,846,883, discloses a piston and shoe arrangement for deflection rolls. The shoe is pivotally mounted in the piston and is in slidable relation with a rotatable shell.
Another recent patent, U.S. Pat. No. 3,879,827, discloses a roll for a rolling mill wherein isolated arrays of hydrostatic bearings may have a larger bearing force at the middle of the roll shell. A further example of the prior art is shown in U.S. Pat. No. 3,802,044 wherein a piston has a hydrostatic bearing interface with a shell roll, the bearing being tiltable and fed with pressurized fluid from a servomotor, the piston being floatable within the nonrotative shaft. Foreign prior art includes British Pat. No. 641,466 and Canadian Pat. No. 976,031 which disclose pressure roller arrangements.
It is seen, therefore, that the prior art encompasses a number of approaches to the problem of providing bearing support for a roll shell. Much of the prior art is comprised of unduly complicated geometry of their pistons and has the potential disadvantage of being unstable during operating conditions, particularly if large deflections of the roll shell are encountered. None of the art teaches the concept of pressurized resilient toroidally shaped bearing pads in conjunction with a pressurizable fluid bearing lubricant.